Just got my first Mercedes a 2005 280SLK and am confused over how the remote key works. My key fob seems to be infrared and only operates on the drivers door sensor, the handbook seems to imply that the key fob is a radio remote. So is it IR or is it radio and should it work when pointed at the passengers door? Did have a problem that the remote wouldn't open the doors, but this was solved by resetting the key fob. Thanks, John.